Pallet work-piece support tables are commonly used in the manufacturing industry for many types of machining and measuring operations. These pallet work-piece tables contain an array of equally spaced threaded holes in which screws can be placed to hold parts in position. The parts can either be directly screwed down to the pallet table to be rigidly held in place or a clamp can be screwed down to the pallet table to hold the part in position. There are various types of clamps currently available that are able to be used on pallet work-piece support tables. One particularly useful type of clamp is commonly referred to as an edge clamp. Three different edge clamp designs have been developed and marketed for this particular application.
Bishop U.S. Pat. No. 4,805,888 uses an eccentrically shaped screw head to cause the clamp to be moved toward the work-piece when rotated. Rotating the eccentrically shaped screw causes the clamp to be moved toward the work-piece by only a small amount, typically around 0.050 inches. The work-piece must be sandwiched between the clamp and work-stop. The work-stop or the clamp must be precisely sized since the amount the clamp is capable of moving is so small. The clamps are produced in only a few specific sizes so the only way to use these types of clamps is to produce custom work-stops for each size work-piece that is to be produced. Alternately, specific pallet work-piece tables could be produced for each size work-piece but their costs are prohibitively high if only small quantities of work-pieces need to be produced, such as in producing prototypes.
Weber U.S. Pat. No. 5,624,106 developed a similarly shaped edge clamp that uses a standard tapered flathead screw instead of the eccentrically shaped screw. The tapered screw is inserted down into a similarly shaped hole in the clamp. The hole has a different angle on the backside of the tapered hole to allow some clearance for the screw. Threading the screw down into the hole of the clamp causes the clamp to be moved toward the work-piece by a similarly small amount, approximately 0.050 inches. As with the Bishop clamp, numerous sized work-stops or clamp sizes would be required to accommodate varying sizes of work-pieces.
Bernstein U.S. Pat. No. 5,310,299 developed a similarly shaped edge clamp that also uses a standard tapered flathead screw instead of the eccentrically shaped screw. The tapered screw is also inserted down into a similarly shaped hole in the clamp and tightened against the pallet work-piece support table. Departing from the Weber design, the hole has an equal angle on the backside of the tapered hole to allow clearance for the screw. Threading the screw down into the hole of the clamp causes the clamp to be moved toward the work-piece by a similarly small amount, approximately 0.050 inches. As with the Bishop and Weber clamps, numerous sized work-stops or clamp sizes would be required to accommodate varying sizes of work-pieces.
Mitee-Bite of Center Ossipee, N.H. manufactures a clamp that uses the Bishop U.S. Pat. No. 4,805,888 type eccentrically shaped screw head in their Series-9 Clamps. As in the other described Bishop design, these clamps move toward the work-piece by only a small amount. To help overcome this problem, they developed an odd shaped hex shape where the distance from the center of the clamp to each of the edges is slightly different. This allows for some additional travel of the clamp.
None of the above clamp designs are flexible enough to allow for various part sizes when used with a pallet work-piece support table that has equally spaced mounting holes. The clamps above are only capable of traveling approximately 0.050″ towards the work-piece so either a custom size work-stop must be designed and used or a dedicated pallet work-piece support table must be created.
To overcome these deficiencies, a novel clamping apparatus was developed which is capable of traveling a large enough distance to hold parts of any size that are capable of fitting on a conventional pallet work-piece support table.